Known processes for producing a polycarbonate (hereinafter referred to as PC) include a process in which an aromatic dihydroxy compound such as a bisphenol is directly reacted with phosgene (interface method) and a process in which an aromatic dihydroxy compound such as a bisphenol and a carbonic diester such as diphenyl carbonate are subjected to a transesterification reaction in a molten state (transesterification method or melt method). With respect to linear PC's among the PC's obtained by such processes, there generally is room for improvement in molding properties such as melt elasticity and melt strength. For improving such molding properties, several techniques have been proposed which comprise copolymerizing a polyfunctional organic compound to form a branched PC (see, for example, patent documents 1 to 3).
In the case where such a branched PC is produced by the melt method using a branching agent heretofore in use in the interface method, the branched PC obtained has a problem that the branching agent undergoes decomposition, etc. at high temperatures and this not only makes it impossible to obtain the desired melt characteristics but results in an impaired hue. This branched PC has not been a commercial product. There has hence been a desire for a branched aromatic polycarbonate which has improved flowability under high load and a satisfactory hue and is hence suitable for use in processing by extrusion and injection molding, especially in applications such as hollow parts formed by blow molding, which necessitates a material having high melt strength and giving an extrudate with excellent shape retention, large panels, and sheets formed by profile extrusion.
[Patent Document 1]                JP-B-44-17149        
[Patent Document 2]                JP-B-47-23918        
[Patent Document 3]                JP-B-60-11733        
The invention provides a branched aromatic polycarbonate of excellent quality and a process for producing the same. More particularly, the invention provides a branched aromatic polycarbonate which has improved flowability under high load and a satisfactory hue and is hence suitable for use in processing by extrusion and injection molding, especially in applications such as hollow parts formed by blow molding, which necessitates a material having high melt strength and giving an extrudate with excellent shape retention, large panels, and sheets formed by profile extrusion. The invention further provides a process for efficiently producing this branched aromatic polycarbonate.